Vladimir Romanovsky, a permafrost expert at the University of Alaska-Fairbanks, has been monitoring the ice in Alaska since emigrating from Russia in 1990. In this series of photos taken in and around Fairbanks, a city built on permafrost, he shows some examples of the effects of thawing soil.

In this image, ground collapsed after surface and ground water saturated the soil. The permafrost layer begins just below the first few inches of "active layer" of soil that thaws and freezes with the seasons. Solid ice is seen in part of the permafrost layer.
(Prof. Vladimir Romanovsky / University of Alaska Fairbanks)
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This permafrost sinkhole appeared in a roadside ditch five miles north of the city. Permafrost is defined as soil that is frozen for two or more years. The top level typically warms in summer and refreezes in winter in subarctic places like Fairbanks. But warmer ground temperatures have caused more thawing in recent decades across Alaska.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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This bicycle path in Fairbanks has become a rollercoaster ride as ice below the pavement melts. Some areas along the path have sunk so low that bikers are warned to steer clear.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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Thawing permafrost can take trees down with it. Here, pines along a trail lose their balance as ice melts in the Tanana River Valley, 20 miles southwest of Fairbanks.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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Many of Fairbanks suburban roads are deformed by thawing permafrost. Crews regularly repair cracks, but larger sunken depressions simply become part of the ride.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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This house two miles north of Fairbanks is a textbook example of what can happen to structures when permafrost starts to thaw.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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Romanovsky says this sinkhole north of Fairbanks demonstrates the most serious effects of thawing permafrost. In this case, the ground thawed from the top, causing melted ice to flow downward and destabilize the ground below.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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This sinkhole appeared five miles north of Fairbanks. Permafrost in the area is typically about 150 feet thick, but it only takes a bit of thawing at the top to start a process that over decades could lead to the melting of all permafrost, Romanovsky says.
(Vladimir Romanovsky / University of Alaska Fairbanks)
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Editor's note:
This image contains graphic content that some viewers may find disturbing.

The permafrost capping the top of the world is irreversibly thawing and within two decades will release more carbon than it now absorbs, scientists calculate in a new study that makes this dire prediction: Up to 60 percent of Earth's permafrost will have thawed out by 2200.

Why care if you don't live in Siberia, Alaska or northern Canada, where thawing permafrost has already buckled roads and swallowed structures?

Because permafrost — which is ground that's been frozen continuously for two or more years — holds enormous amounts of carbon in the form of frozen plant matter, and adding more of that to the atmosphere would raise temperatures even higher, scientists say.

Philip Seymour Hoffman withdrew a total of $1,200 from an ATM at a supermarket near his New York City apartment the night before he was found lifeless in his bathroom with a syringe still in his left arm, sources told NBC News.

"The amount we expect to be released by permafrost is equivalent to half of the amount of carbon released since the dawn of the Industrial Age," Kevin Schaefer, lead author and a scientist at the National Snow and Ice Data Center, said in a statement. "That is a lot of carbon."

Here's another way to look at it: The carbon predicted for release through 2200 is about one-fifth of the total amount in the atmosphere today.

Earlier studies have estimated the carbon released from the "active layer" of soil a few inches above the permafrost — soil that freezes and thaws in winter and summer.

But "ours is the first study to estimate how much carbon could be released from thawing permafrost and when," Schaefer told msnbc.com.

If anything, the estimate is very conservative, Schaefer says, because it doesn't include a known "feedback" mechanism: that permafrost carbon release will certainly add to warming, which in turn will accelerate the thawing and then even more carbon emissions.

Moreover, the experts wrote, that "source" impact "is strong enough to cancel 42–88 percent of the total global land sink" absorbing carbon.

Having these estimates, Schaefer said, means that policymakers trying to reach set carbon-reduction targets will "have to reduce fossil fuel emissions that much lower than previously calculated to account for this additional carbon from the permafrost. Otherwise we will end up with a warmer Earth than we want."

Schaefer expects the U.N. Intergovernmental Panel on Climate Change will incorporate his team's estimates in its next climate policy reports. And "we're working with other scientists, they are already putting permafrost carbon in their models," he said.

The study was published online this week in the peer-reviewed journal Tellus. Funding came from NASA, NOAA and the National Science Foundation.